The Car Engine Shakes When Starting – What to Do?

Table: Reasons and Solutions of Car Engine Shaking When Starting

After some testing and twigging, we have found some easy solutions for you. The table below will give you a quick overview.

Reasons	Solutions
Loose Engine and Bad Motor Mounts	Replace the mounts with a new one
Poor Fuel Pressure	Check and replace the fuel pump or  pressure regulator
Engine Misfire	Repairing the combustion components
Starter Motor Problem	Replace the starter motor
Improper Timing Belt	Polish and adjust the belt

5 Main Reasons Why Your Car Engine Shakes When Starting

A shaky engine is always bad news. Before we proceed to the solution, you should always make sure that your engine is cold and the negative cable is unplugged.

Bad Engine Motor Mounts

A motor mount controls the engine vibration. It isolates the engine from the vehicle’s body and holds it in place. But if the mount’s rubber becomes old or worn out, it will crack, and your engine will vibrate when that happens.

Fix

The best possible solution here is to replace the bad mount with a new one. You can do it by following these steps:

Step One: Support The Engine

First, you need a hydraulic jack or engine support bar to support the engine. After that, use an engine leveler to lift the engine a bit. This way, you will have better access to the mount.

Step Two: Unbolt the mount

The engine mount is securely placed with some bolts. You have to unscrew those bolts. Then, take out the mount from its place.

Step Three: Replace the Engine Mount

Now, put the new mount in that place and secure it properly. After that, position the engine on top of the mount and lower it.

Step Four: Check Loose Components

Before the test run, thoroughly check every wire under the car’s hood. If you find any loose component, adjust it tightly in place.

Here is a video link to guide you better.

Poor Fuel Pressure

If the fuel system doesn’t have enough pressure, your car’s engine won’t get enough oil and air. So, when you ignite your car in this situation, the engine vibrates. Poor fuel pressure usually occurs due to a pressure regulator or fuel pump.

Fix

Changing the faulty part can solve the problem:

Step One: Locating

There are two types of systems. One is mechanical return, and the other is return less. If you have a mechanical return system, the fuel regulator will be at the tail of the fuel rail. In a returnless system, it is joined with the fuel tank. The fuel pump should be inside the gas tank.

Step Two: Replacing the Regulator

First, you have to check the regulator for any wear and tear. If you find that it’s damaged, then change it. For that, you have to first detach the fuel pressure sensor.

Then, remove the bolt from the regulator and put the new one in that place. Finally, start your car and see if the vibration is still there.

Step Three: Changing the Fuel Pump

If there is no damage in the regulator or the engine still vibrates, you might have to change the fuel pump. For that, you have to jack your car and unscrew the bolts holding your tank.

Open the ring-shaped top and take out the plastic assembly. The fuel pump is inside it. Unscrew the bolts of the cover, and take out the pump. Place the new one and put everything back in place. Now, do a test run.

Engine Misfire

To function properly, the engine of your car needs four strokes. A certain ratio of air and fuel, compression, power, and spark. When these four strokes don’t meet, a misfire happens. Even the check engine light pops up.The primary cause is a bad spark plug or a clogged fuel injector.

Fix

Below are the steps to fix this problem.

Step One: Take out and Inspect the Spark Plug

The spark plugs are typically connected to thick wires or ignition coils, which run to the engine. Now, hold the thick wire boot and pull it out. After that, with a spark plug socket, bring out the plug from the whole and then inspect it. If the plug’s tip has turned brown, you’ll have to change it.

Step Two: Replace the Plug

To install a new spark plug, you’ll have to place the plug in the whole and tighten it up with a plug socket. Finally, put the wire boot in its previous place.

Step Three: Locate and Replace the Fuel Injectors

First, you’ll have to unscrew the bolts holding the rail. Then, lift the rail, and you will find the four injectors. If you wiggle them a bit, they will come off.

Inspect all the injectors and put the new one in the damaged ones place. After that, ignite your car for testing.

Starter Motor Problem

The starter motor transmits power to your engine from the battery and spins the flywheel. When it can’t connect to the battery or engage the flywheel, the engine starts to shake.

Fix

In that case, you have to install a new starter motor like this:

Step One:  Locating

The starter motor is  right below the point where your flywheel and transmission meet. You have to access it from underneath your car.

Step Two: Replacing

Now,  unscrew the bolts, and the motor will come right off. Now, place the new one and screw it in. Put your car down and start it up to test the situation.

Improper Timing Belt

The timing belt synchronizes the rotation of the two crankshafts. It connects the bottom to the top to run the valves. A worn down or misadjusted belt won’t be able to power up the engine properly and vibration can happen.

Fix

In this case, follow our instructions:

Step One: Locating

You can find the timing belt underneath the engine. It’s covered with the engine cover.

Step Two: Adjustments

Most modern vehicles don’t need belt adjustments. Cars nowadays come with an automatic transitioner. But cars made before 2000 will need adjustments. You can use a spring tension tool to tighten or loosen the belt.

Step Three: Replace

Now, if there is no adjustment issue, then all there is left to do is replace it. For that, you have to loosen the bolt of the tension pulley. Once it’s loose, remove the belt, place the new one, and then tighten the bolt. This should make your engine run smoothly.

Why does my car shake when starting up cold?

The phenomenon of a car shaking when starting up in cold weather can be attributed to various factors.

Firstly, a dead battery can struggle to provide sufficient power in cold temperatures, making engine ignition challenging. To address this, ensuring a fully charged battery and using a battery blanket for warmth is recommended.

Cold engine oil can also contribute to difficulty in starting, leading to rough idling and stalling. Using a thicker oil and checking levels before winter can alleviate this issue.

Additionally, a clogged fuel filter, spark plug failure, and changes in tire pressure due to temperature drops are potential culprits for the unsettling vibrations. Regular maintenance, such as replacing clogged filters and damaged spark plugs, checking tire pressure, and aligning wheels, can effectively mitigate these concerns. Brake problems arising from cold weather, such as hardened brake pads and warped rotors, should be addressed by professional inspection and replacement.

Beyond these common issues, worn engine mounts, low transmission fluid levels, incorrect gear ratios, and worn transmission mounts can also contribute to the unsettling phenomenon of a car shaking during cold starts.

If the vibrations persist after the engine warms up, further investigation is recommended to identify and address any underlying problems.